Folliculin (FLCN) Antibody

Background

Folliculin (FCLN) is a tumor suppressor protein encoded by the FLCN gene and plays a key role in cellular energy sensing, metabolic regulation, and mTOR signaling pathways. It is widely implicated in Birt-Hogg-Dubé syndrome (BHD), a rare autosomal dominant disorder associated with renal cell carcinoma, lung cysts, and fibrofolliculomas. FCLN functions as a GTPase-activating protein (GAP) for RagC and RagD GTPases, facilitating the activation of the mTORC1 complex on lysosomal membranes in response to nutrient availability. Dysregulation of FCLN can lead to abnormal mTORC1 signaling, promoting unchecked cellular proliferation and metabolic imbalances. Folliculin is expressed in a variety of tissues, with high levels in the kidney, lung, and skin, correlating with the phenotypic manifestations of BHD. Structural studies indicate that FCLN forms a complex with folliculin-interacting proteins (FNIP1 and FNIP2), enhancing its role in AMPK regulation and energy homeostasis. Emerging research suggests that FCLN also influences autophagy and lysosomal biogenesis, positioning it as a critical regulator of cellular stress responses. Loss of function or mutations in FCLN disrupt cellular homeostasis, making cells more susceptible to oncogenic transformation. FCLN's interactions with FNIPs and its role in integrating metabolic and nutrient signals highlight its significance in maintaining cellular and tissue-level equilibrium.